1. Field of the Invention
The present invention relates to a structure and method for manufacturing electronic components and piezoelectric-resonant components used, for example, as piezoelectric filters. Particularly, the present invention relates to a method for manufacturing electronic components and piezoelectric-resonant components, wherein an adhesive-printing method is improved for laminating a plurality of mother substrates via an adhesive agent, and also relates to an electronic component and a piezoelectric-resonant component manufactured by such a method.
2. Description of the Related Art
Conventionally, a layered structure made of a piezoelectric substrate is sandwiched by encapsulating substrates and is applied to a piezoelectric-resonant component so as to provide a space for a piezoelectric-vibration unit to vibrate. A piezoelectric-resonant component of this type is disclosed in, for example, Japanese Unexamined Utility Model Publication No. 59-127330.
Referring to FIG. 7, which is an exploded perspective view of the prior art piezoelectric-resonant component, encapsulating substrates 52 and 53 are laminated with a piezoelectric substrate 51 therebetween via adhesive layers 54 and 55.
Piezoelectric-vibration units 51a and 51b are defined by exciting electrodes that are disposed on an upper surface and a lower surface of the piezoelectric substrate 51. The adhesive layers 54 and 55 include circular openings 54a, 54b, 55a, and 55b in order to define spaces for the piezoelectric-vibration units 51a and 51b to vibrate. The adhesive layers 54 and 55 are provided by a squeegee-printed adhesive agent on the upper and the lower surfaces of the piezoelectric substrate 51. The squeegee-printing is performed so that the adhesive is not printed at areas where the openings 54a to 55b are located.
A layered product 56, as shown in FIG. 8, is obtained by printing the adhesive agent defining the adhesive layers 54 and 55, and then bonding the encapsulating substrates 52 and 53. A piezoelectric-resonant component is completed by providing external electrodes (not shown) on the side surfaces of the layered product 56.
In a manufacturing process that is actually used in practice, the above layered product is produced from a mother substrate. That is, an adhesive agent is printed on a mother piezoelectric substrate, mother encapsulating substrates are laminated thereon, and a mother layered product is produced, which is cut along the thickness direction, thereby obtaining the above-described layered product 51 which defines a single piezoelectric-resonant component.
However, a problem with the piezoelectric-resonant components that are produced as described above is that the thickness of the adhesive layers varies, whereby gaps between the adhesive layers 54 and 55 and the encapsulating substrates 52 and 53 are likely to result.
Specifically, the thickness of the adhesive-printed layers that are laminated on the upper and the lower surfaces of the mother piezoelectric substrate are likely to vary depending on their position because the adhesive agent is scratched off by a squeegee rubber in the squeegee-printing method. Also, the adhesive layers are likely to be thicker at the outer edges of the adhesive-printed areas and at the margin of the openings 54a, 54b, 55a, and 55b, and are likely to be thinner at other areas.
Therefore, when a mother layered product is produced, for example, from a mother piezoelectric substrate constituted by the piezoelectric substrates 51 assembled in a matrix pattern, the adhesive layers are thin at the cut sections of the outer edges of the adhesive layers 54 and 55 of the piezoelectric-resonant components, which were obtained by cutting the mother layered product. The adhesive layers 54 and 55 are thinner at a flat section of the cut surface of the periphery indicated by arrow A than at the margin of the openings 54a and 54b. As a result, gaps are produced at the periphery of the layered product 56 due to the reduced thickness of the adhesive layers 54 and 55, thereby causing problems, such as the external electrodes becoming loosened and/or disconnected.
To overcome the problems described above, preferred embodiments of the present invention provide a method for manufacturing electronic components that prevents disconnection and bonding strength reduction due to thickness irregularities in the adhesive layers of the electronic components. Further, preferred embodiments of the present invention provide a method for manufacturing piezoelectric-resonant components and a piezoelectric-resonant component manufactured by the method, that produces a reliable piezoelectric-resonant component by eliminating gaps due to thickness irregularities in the adhesive layers at the periphery of the piezoelectric-resonant component, when the components are produced from a mother layered product that has a mother piezoelectric substrate including energy-trap type piezoelectric-vibration units.
A method for manufacturing electronic components, according to a first preferred embodiment of the present invention, includes the steps of obtaining a mother layered product by laminating at least two mother substrates by adhesive-printing on one of the mother substrates, and producing each of the electronic components by cutting the mother layered product along a thickness direction thereof, wherein the adhesive-printing is performed in a manner that the adhesive-printed area is provided with a plurality of pass-through openings over which an adhesive layer is not formed.
According to the first preferred embodiment, the plurality of pass-through openings are preferably provided in the vicinity of the periphery of each of the electronic components.
In the method for manufacturing electronic components according to the first preferred embodiment of the present invention, adhesive-printing is performed on the mother substrate so that the plurality of the pass-through openings over which the adhesive layer is not defined are formed in the adhesive-printed area. Because an adhesive layer is thick at locations surrounding the pass-through openings, gaps caused by irregularities in the thickness of the adhesive layer of the layered product can be avoided.
Particularly, when the plurality of pass-through openings are disposed in the vicinity of the periphery of an electronic component, the gaps at the outer side surface of the electronic component can be greatly reduced, thereby reducing the risk of short-circuiting the outer electrodes, thus producing a highly moisture-resistant electronic component.
A method for manufacturing piezoelectric-resonant components, according to a second preferred embodiment of the present invention, includes the steps of preparing a mother piezoelectric substrate including a plurality of energy-trap type piezoelectric-vibration units, and preparing a first mother encapsulating substrate and a second mother encapsulating substrate to be laminated with the mother piezoelectric substrate disposed therebetween, adhesive-printing on an upper surface and a lower surface of the mother piezoelectric substrate except for annular areas around the piezoelectric vibration units, in such a manner that a plurality of pass-through openings are formed in the adhesive-printed areas of the adhesive layers, producing a mother layered product by laminating the first and the second mother encapsulating substrates with the mother piezoelectric-substrate disposed therebetween, and producing each of the piezoelectric-resonant components by cutting the mother layered product along a thickness direction thereof.
In the method for manufacturing piezoelectric-resonant components, according to the second preferred embodiment of the present invention, adhesive-printing is performed so that a plurality of pass-through openings are formed in the adhesive printed area, the adhesive-printing being performed on the upper and lower surfaces of the mother piezoelectric substrate except for annular areas around the piezoelectric-vibration units. Therefore, the adhesive layer is thick enough around the plurality of pass-through openings of the mother layered product, which is produced by the first and the second mother encapsulating-substrates being laminated, to reduce the risk of gaps being formed between the mother piezoelectric substrate and the first and second mother encapsulating substrates.
By disposing the pass-through openings in the vicinity of the periphery of the piezoelectric-resonant component, the gaps at the outer side surfaces of the completed piezoelectric resonant component can be prevented, whereby a reliable piezoelectric-resonant component is provided.
A piezoelectric-resonant component according to a third preferred embodiment of the present invention, includes a piezoelectric substrate, a first encapsulating substrate and a second encapsulating substrate laminated with the piezoelectric substrate disposed therebetween, and a first adhesive layer and a second adhesive layer for bonding the piezoelectric substrate with the first and the second encapsulating substrates, wherein the first and the second adhesive layers are provided at locations of the piezoelectric substrate except for an area around piezoelectric-vibration units included in the piezoelectric substrate, and a plurality of pass-through openings are provided in the adhesive layers.
In the piezoelectric-resonant component according to the third preferred embodiment of the present invention, the plurality of pass-through openings are preferably provided in the vicinity of the periphery of the piezoelectric-resonant component.
In the piezoelectric-resonant component according to the third preferred embodiment of the present invention, the first and the second encapsulating substrates are laminated with the piezoelectric substrate disposed therebetween via the first and the second adhesive layers. The first adhesive layer and the second adhesive layer are provided at locations on the piezoelectric substrate except around the piezoelectric vibration units included in the piezoelectric substrate. Moreover, a plurality of the pass-through openings are provided in the adhesive layers. Therefore, the adhesive layers are thick enough at locations around the pass-through openings, thereby providing high bonding-reliability of the first and the second encapsulating substrates with the piezoelectric substrate, and reducing the risk of gaps caused by the thin adhesive layers.
When the plurality of pass-through openings are provided in the vicinity of the periphery of the piezoelectric-resonant component, gaps at the outer side surface of the piezoelectric-resonant component are prevented, whereby the risk of short-circuiting of the terminal electrodes is reduced, thus, the moisture resistance is greatly improved.
Other features, elements, aspects and advantages of the present invention will become apparent from the following detailed description of preferred embodiments of the invention which refers to the accompanying drawings.